CD43 plays both antiadhesive and proadhesive roles in neutrophil rolling in a context-dependent manner.

As the first step in the recruitment of neutrophils into tissues, the cells become tethered to and roll on the vessel wall. These processes are mediated by interactions between the P- and E-selectins, expressed on the endothelial cells of the vessel wall, and their ligands, expressed on the neutrophils. Recently, we reported that CD43 on activated T cells functions as an E-selectin ligand and thereby mediates T cell migration to inflamed sites, in collaboration with P-selectin glycoprotein ligand-1 (PSGL-1), a major P- and E-selectin ligand. Here, we examined whether CD43 on neutrophils also functions as an E-selectin ligand. CD43 was precipitated with an E-selectin-IgG chimera from mouse bone marrow neutrophils. A CD43 deficiency diminished the E-selectin-binding activity of neutrophils when PSGL-1 was also deficient. Intravital microscopy showed that the CD43 deficiency significantly increased leukocyte rolling velocities in TNF-alpha-stimulated venules blocked with an anti-P-selectin mAb, where the rolling was mostly E-selectin dependent, when PSGL-1 was also absent. In contrast, in venules with trauma-induced inflammation, where the rolling was largely P-selectin dependent, the CD43 deficiency reduced leukocyte rolling velocities. Collectively, these observations suggest that CD43 generally serves as an antiadhesive molecule to attenuate neutrophil-endothelial interactions, but when E-selectin is expressed on endothelial cells, it also plays a proadhesive role as an E-selectin ligand.